The invention relates to a road marking system.
The invention further relates to a lighting module for use in a road marking system, a road surface provided with a road marking system, and a method of manufacturing a road marking system.
Such road marking systems are used in traffic guidance systems for marking paths to be followed by means of transport, such as roads for cars and other road users and runways for airplanes. One of the methods used by traffic planners in their efforts to reduce traffic jams is a so-called tidal flow system. In such a dynamic system, the direction of the traffic on multilane roads is changed in one or several lanes in accordance with the direction of the main flow of traffic. In an alternative embodiment, the number of lanes available for traffic moving in a certain direction is increased or decreased in dependence on the amount of traffic offered. It is a problem in these methods to indicate the direction of the desired traffic flow for a certain traffic lane in a flexible manner, or to change the subdivision of the road in a flexible manner. Known means for indicating the desired direction of the traffic flow comprise signaling lights next to or above the road.
Said road marking systems may have static applications in addition to their use as dynamic road marking systems. Static applications of road marking systems comprise the markings of portions of roads (for example straight portions or bends) which direct the traffic under certain weather conditions, for example during fog, rain, iciness, etc., and/or under certain lighting conditions, for example daylight, twilight, low position of the sun, night, etc.
Road marking systems may be provided in a road surface of the road, but also next to and/or above the road, for example on a crash barrier next to the road.
The principle of dynamic road marking is described in WO-A 00/020691 (PHN 17.533). This road marking system utilizes light emitted in the direction of the road user (driver), for example for realizing a flexible driving lane arrangement. A seemingly continuous (white) line is realized in that light dots present in a lighting module are placed at suitable distances from one another and are switched on. The impression of a continuous line is created because the road user perceives the road surface from a certain distance and at an angle. Switching on and off of the light in segments changes a dotted or interrupted line into a closed or continuous line marking. Such segments are, for example, three metes long, for example comprising twelve lighting modules with mutual spaces of approximately 25 cm. Thus, for example, segments of said length may be switched such that only one out of every four segments is burning, so that a broken line with the length of one segment followed by three times the length of one segment without light each time is created. A seemingly continuous (white) line is visible if all segments are switched on. It is also possible to move the lines through a suitable switching on or off of a line. In this manner, a normal two-lane road segment may be transformed into, for example, a road with three narrowed driving lanes (possibly in combination with a reduced maximum speed). Such road marking systems dynamically increase the capacity of an existing road. The lighting modules may also be used for alternative applications in which the mutual distances between the lighting modules are variable. Thus it is also possible, for example, to displace the lines (seemingly) in that a strip is switched on and off in a suitable manner.
WO-A 00/020691 and WO-A 01/92641 describe various embodiments of lighting modules which are also provided in the road surface. WO-A 01/92641 describes a sawcut arrangement for providing (electrical) supply and control cables in which sawcuts are provided which extend in longitudinal direction in the road surface. In this case an approximately 2.5 cm wide cable duct is sawn into the surface of the road to a depth that varies between 3 and 10 cm. The cable or cables is or are laid in such a cable duct, which is usually filled at the upper side with road metal or fine gravel. At the road surface level, the cable duct is usually closed by means of a bituminous or concrete-type substance. WO-A 01/92641 further describes lighting modules in the form of half discs into which the cable is introduced adjacent the surface of the road.